I know several people in two-year programs who are perfectly happy with that choice. Personally, I'm glad I ended up at a three-year program. lagoon91 already mentioned most of the reasons why I feel that way, but I do think the point about additional time to work on theses bears repeating. For most MFAs, thesis is more a stopping point than a flawless manuscript. That third year is valuable time to re-write/revise/refine.